/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace Spring;

/// <summary>
/// A simple StopWatch implemetion for use in Performance Tests
/// </summary>
/// <example>
/// The following example shows the usage:
/// <code>
/// StopWatch watch = new StopWatch();
/// using (watch.Start("Duration: {0}"))
/// {
///    // do some work...
/// }
/// </code>
/// The format string passed to the start method is used to print the result message.
/// The example above will print <c>Duration: 0.123s</c>.
/// </example>
/// <author>Erich Eichinger</author>
public class StopWatch
{
    private DateTime _startTime;
    private TimeSpan _elapsed;

    private class Stopper : IDisposable
    {
        private readonly StopWatch _owner;
        private readonly string _format;

        public Stopper(StopWatch owner, string format)
        {
            _owner = owner;
            _format = format;
        }

        public void Dispose()
        {
            _owner.Stop(_format);
            GC.SuppressFinalize(this);
        }
    }

    /// <summary>
    /// Starts the timer and returns and "handle" that must be disposed to stop the timer.
    /// </summary>
    /// <param name="outputFormat">the output format string, that is used to render the result message. Use '{0}' to print the elapsed timespan.</param>
    /// <returns>the handle to dispose for stopping the timer</returns>
    public IDisposable Start(string outputFormat)
    {
        Stopper stopper = new Stopper(this, outputFormat);
        _startTime = DateTime.Now;
        return stopper;
    }

    private void Stop(string outputFormat)
    {
        _elapsed = DateTime.Now.Subtract(_startTime);
        if (outputFormat != null)
        {
            Console.WriteLine(outputFormat, _elapsed);
        }
    }

    public DateTime StartTime
    {
        get { return _startTime; }
    }

    public TimeSpan Elapsed
    {
        get { return _elapsed; }
    }
}
